International Journal of Engineering Research & Science (IJOER)
ISSN: [2395-6992]
[Vol-2, Issue-10, October- 2016]
Comparison of Thermal Properties in Composites of PHB Using Rice Husk Ash or Talc as Filler Ivonete O. Barcellos1, Leila Denise Alberti2, Doris Zwicker Bucci3, Ricardo A.N. Ferreira4 1,2,3
Departamento de Química, Universidade Regional de Blumenau-FURB, Blumenau, SC -Brazil. *E-mail: iob@furb.br 4 Centro de Desenvolvimento da Tecnologia Nuclear CDTN- UFMG, Belo Horizonte, MG- Brazil.
Abstract— This study has been conducted in order to use rationally rice husk ash (RHA) since it is one of the most abundant industrial waste. With the purpose of comparing fillers, composites of PHB (polyhydroxybutyrate) with RHA and PHB with talc (TA), were obtain by twin-screw extrusion and injection molding techniques and characterized by the use of Laser Flash Method and Differential Scanning Calorimetry (DSC). The thermal conductivity value displayed by PHB polymer was 0.419 W∙m-1∙K-1 while the composites values were slightly higher, due to the increasing content of the filler. PHB/RHA composite showed maximum values 0.456 W∙m-1∙K-1 and, PHB/TA composite was 0.492 W∙m-1∙K-1. As regards to the DSC it can be stated that the presence of filler does not change significantly the thermogram curve, as evidenced by the endothermic peak at 172.96°C, 173.61°C and 171.65°C to PHB, PHB/RHA (85/15) and PHB/TA (85/15), respectively. Fillers from waste contribute to sustainable materials. Keywords— PHB (polyhydroxybutyrate), Composites, Rice Husk Ash, Talc, Laser Flash Method.
I.
INTRODUCTION
Composites have gained more space in various industry segments mostly because these materials make possible a good synergy in the interaction between the different components forming it, resulting in a range of properties inherent to the material and more interesting economic and environmentally friendly than the original components [1-5]. PHB is a biodegradable and biocompatible thermoplastic polymer that can be produced by bacteria from carbohydrates in bioreactors [6]. Its mechanical properties are generally restricted to certain uses due to its fragility. Furthermore, PHB has a narrow processing window and thermal instability near 180 °C [7-10]. In order to be accepted on a large scale, it is evident the need for improvement of its properties and processability is necessary. This can be obtained by adding functional fillers. Rice husk ash (RHA) is an abundant waste generated from drying rice operation in several countries [11]. The world rice production in the period of 2006 to 2007 was approximately 600 million tons. These represent a generation of 145 million tons of rice husk residue [12]. RHA contends a large amount of silica (SiO2) at least 90% [13, 14]. Despite the great possibilities of using this residue [15], its main application remains as landfill, which is an unsatisfactory solution from both the environmental and economic points of view. Studies have been conducted in order to facilitate the RHA use in a more rational way [16-19]. The use of food waste in the production of bioplastic composite can be a good way to reduce cost of these polymers and the amount of residue to the environment [20]. The accurate determination of the thermal properties of a polymer is critical in many processes and engineering projects. Thermal conductivity is a property of transport that is directly linked to the rate of thermal energy transfer by diffusion through a material medium [21].The thermal diffusivity, in particular, is important in problems involving non-steady state, such as in heating and cooling a polymer and in applications involving thermal insulation. It is a fundamental processing property in injection molding process, for the determination of molding cycle time [22]. The aim of this present work is to prepare biodegradable composites that can be used as insulators for technological applications and more environmentally friendly, since it minimizes the problems due the tremendous amounts of plastic waste. For comparison purpose, composite specimens of poly (3-hydroxybutyrate) (PHB) using rice husk ash (RHA) as filler in different percentages were prepared, as well as the use of talc (TA) as conventional filler. They were obtained and evaluated through their thermal properties by Laser Flash Method and Differential Scanning Calorimetry (DSC). The physical-chemical, mechanical properties and biodegradability of PHB composites are presented in [2, 3]. Page | 13